1. Field of Invention
This invention relates to an apparatus for changing transmission fluid, and, optionally, flushing the transmission components and exchanging the fluid with fresh fluid.
2. Description of Prior Art
Many consumer and industrial devices use automatic transmissions filled with automatic transmission fluid (ATF) as the working fluid. At regular intervals, this automatic transmission fluid should be removed from the transmission and replaced with fresh fluid as the fluid properties degrade with time and use and entrain contaminants and debris which are not fully removed by the filter in the transmission.
Automatic transmissions require transmission fluid because such fluid is employed in part as a driving means within the transmission and is additionally employed to lubricate the internal components within such transmissions. Over time such fluid becomes less viscous and thus less efficient in lubricating such components. It is, therefore, desirable to periodically perform an exchange of fluid to maintain the viscosity of such fluid within the transmission and to maintain the cleanliness of the transmission and thereby increase the useful life of the transmission. A complete exchange of fluid is preferred so that the used fluid as well as undesirable foreign matter contained therein is completely removed and is replaced with new, more viscous fluid.
When considering the typical personal automobile, the process usually involves removing the transmission pan from the transmission and allowing the fluid to drain therefrom. The pan typically holds from 1 to 5 quarts of a total 7 to 15 quart capacity of the transmission. Thus, emptying the pan and then adding that amount of new fluid only serves to dilute the used fluid with some 15-50% of new fluid. After the pan has been drained, it is then reinstalled and new transmission fluid is added through the dipstick tube to bring the transmission to the proper fluid level. However, this process has a significant disadvantage. Specifically, the fluid that is present at a given time in the oil pan is only a small portion of the fluid actually in the transmission. Typically, a good deal of the transmission fluid remains in the control circuits of the transmission, the torque converter and the transmission cooler. Therefore, a traditional transmission fluid change will really only change about one-quarter to one-third of the transmission fluid and the transmission will be forced to operate with a mixture of old fluid and new fluid, thereby reducing its efficiency. More particularly, this invention relates to methods and apparatus in which a cleansing composition is automatically introduced into the transmission to cleanse the entire transmission system and then the fluid is automatically flushed from the transmission as it is being refilled.
In the field of devices for flushing and filling fluids in an automobile engine or transmission, various different embodiments of such apparatus have been known for a number of years and, by way of example, forms of such embodiments can be found in U.S. Pat. Nos. 4,095,673, 4,674,456, 5,056,621, 5,427,202, 5,447,184, 5,456,295, 5,318,080 and 5,626,170.
Prior art flushing and filling apparatus have some disadvantageous features associated with them. For example, flushing and filling automatic transmissions with fluid or oil according to many prior art methods is a relatively time-consuming, cumbersome and inefficient process. The conventional method is to replace the fluid housed in the pan of the transmission. It is difficult to remove all of the fluid and to also clean the interior of the system.
More recently, there have been effort""s to change all of the fluid in an automobile""s transmission by disconnecting a fluid tube and draining the fluid into a waste oil dump while manually pouring new fluid into the transmission dipstick hole. This procedure has proven to be inefficient, inadequate and so time consuming that it has failed to gain broad popularity.
Another prior method involved disconnecting a transmission fluid cooler line and allowing one end of such cooler line carrying used fluid to drain freely, while the other end of the line was connected to a pressurized tank which injected unused fluid into the cooler line connected to the transmission. One major disadvantage associated with this method is that, in many instances, the rate at which fluid exits the transmission cannot be matched by the rate at which unused fluid is injected into the transmission because the transmission, due to internal resistances, cannot accept fluid at the same rate as the rate at which used fluid is flowed by the transmission pump into an unrestricted cooler line. As such, there is a risk that the fluid seals, rear bearings and other internal components of the transmission could suffer damage due to the progressively diminishing level of fluid in the transmission during such a process. This difficulty is compounded by the fact that the flow resistance varies with the different models of transmissions.
Other work in this field has led to the proposal of a transmission changer including air pressurized tanks for supply and extraction of transmission fluid via the transmission cooling lines. Others use a supply pump device for supplying transmission fluid at a controlled rate to the transmission and a flow control device to control the rate of flow in the supply tube so the volume of unused fluid does not exceed the volume of used fluid flowed from the transmission. So the desired fluid level may be maintained in the transmission throughout the exchange process.
Briefly and in general terms, the present invention provides an automatic transmission fluid cleaner, removal and replacement device that includes a drain tube that releasably and selectively connects to an additive reservoir and a variable drain reservoir and includes a fill tube releasably connected to a disconnected cooler line that normally conducts used transmission fluid to the radiator of the vehicle, and to a port on the radiator to which the cooler line is normally connected. The drain tube is selectively connected to an additive reservoir and the disconnected cooler line is connected to the additive reservoir such that as the fluid in the transmission is circulated as connected the additive reservoir will be in the line of flow and will inject a cleaning additive into the transmission system and then collectively connected at their other ends to a drain and fill cylindrical tank which has chambers therein which are separated by a rotating wand about it""s longitudinal axis to cause used fluid to be collected and new fluid to be injected into the transmission system. The transmission fluid pump is employed to flow used fluid through the disconnected cooler line and into the drain reservoir while the supply pump simultaneously injects unused fluid through the supply tube and into the cooler port of the radiator.